WAEC Physics 2012 Theory — Question 10

Model answer

Wave-particle duality is the concept that light exhibits both wave-like and particle-like properties, depending on the type of experiment or observation being carried out. As a wave, light exhibits phenomena such as interference, diffraction, refraction and polarization — for example, Young's double-slit experiment demonstrates interference patterns typical of waves. As a particle (photon), light exhibits the photoelectric effect, in which light striking a metal surface ejects electrons in a manner that can only be explained if light is considered to consist of discrete packets (photons) of energy, each carrying energy E=hf. Thus, light behaves as a wave in phenomena like interference and diffraction, and as a particle in phenomena like the photoelectric effect.